/* Copyright 2016 The TensorFlow Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/
#ifndef TENSORFLOW_CORE_UTIL_MEMMAPPED_FILE_SYSTEM_WRITER_H_
#define TENSORFLOW_CORE_UTIL_MEMMAPPED_FILE_SYSTEM_WRITER_H_

#include <memory>
#include <vector>

#include "tensorflow/core/framework/tensor.h"
#include "tensorflow/core/platform/env.h"
#include "tensorflow/core/util/memmapped_file_system.h"
#include "tensorflow/core/util/memmapped_file_system.pb.h"

namespace tensorflow {

// A class for saving into the memmapped format that can be read by
// MemmappedFileSystem.
class MemmappedFileSystemWriter {
 public:
  MemmappedFileSystemWriter() = default;
  ~MemmappedFileSystemWriter() = default;
  absl::Status InitializeToFile(Env* env, const std::string& filename);
  absl::Status SaveTensor(const Tensor& tensor,
                          const std::string& element_name);
  absl::Status SaveProtobuf(const protobuf::MessageLite& message,
                            const std::string& element_name);
  // Writes out the directory of regions and closes the output file.
  absl::Status FlushAndClose();

 private:
  absl::Status AdjustAlignment(uint64_t alignment);
  void AddToDirectoryElement(const std::string& element_name, uint64_t length);
  MemmappedFileSystemDirectory directory_;
  // The current offset in the file, to support alignment.
  uint64_t output_file_offset_ = 0;
  std::unique_ptr<WritableFile> output_file_;
  MemmappedFileSystemWriter(const MemmappedFileSystemWriter&) = delete;
  void operator=(const MemmappedFileSystemWriter&) = delete;
};

}  // namespace tensorflow

#endif  // TENSORFLOW_CORE_UTIL_MEMMAPPED_FILE_SYSTEM_WRITER_H_
